[PATCHv3 1/2] arch: Move CONFIG_DEBUG_RODATA and CONFIG_SET_MODULE_RONX to be common
From: Laura Abbott <hidden>
Date: 2017-02-07 00:32:16
Also in:
linux-arm-kernel, linux-s390, lkml
Subsystem:
arm port, arm64 port (aarch64 architecture), documentation, parisc architecture, s390 architecture, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Russell King, Catalin Marinas, Will Deacon, Jonathan Corbet, "James E.J. Bottomley", Helge Deller, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
There are multiple architectures that support CONFIG_DEBUG_RODATA and CONFIG_SET_MODULE_RONX. These options also now have the ability to be turned off at runtime. Move these to an architecture independent location and make these options def_bool y for almost all of those arches. Signed-off-by: Laura Abbott <redacted> --- v3: Make these configs selectable for arm. Include some documentation about how the setup of the optional Kconfigs work as well. Stop spelling 'kenrel' in prompt text. --- Documentation/security/self-protection.txt | 6 ++++++ arch/Kconfig | 34 ++++++++++++++++++++++++++++++ arch/arm/Kconfig | 4 ++++ arch/arm/Kconfig.debug | 11 ---------- arch/arm/mm/Kconfig | 12 ----------- arch/arm64/Kconfig | 5 ++--- arch/arm64/Kconfig.debug | 11 ---------- arch/parisc/Kconfig | 1 + arch/parisc/Kconfig.debug | 11 ---------- arch/s390/Kconfig | 5 ++--- arch/s390/Kconfig.debug | 3 --- arch/x86/Kconfig | 5 ++--- arch/x86/Kconfig.debug | 11 ---------- 13 files changed, 51 insertions(+), 68 deletions(-)
diff --git a/Documentation/security/self-protection.txt b/Documentation/security/self-protection.txt
index 3010576..f41dd00 100644
--- a/Documentation/security/self-protection.txt
+++ b/Documentation/security/self-protection.txt@@ -56,6 +56,12 @@ CONFIG_DEBUG_SET_MODULE_RONX, which seek to make sure that code is not writable, data is not executable, and read-only data is neither writable nor executable. +Most architectures have these options on by default and not user selectable. +For some architectures like arm that wish to have these be selectable, +the architecture Kconfig can select ARCH_OPTIONAL_KERNEL_RWX to enable +a Kconfig prompt. CONFIG_ARCH_OPTIONAL_KERNEL_RWX_DEFAULT determines +the default setting when ARCH_OPTIONAL_KERNEL_RWX is enabled. + #### Function pointers and sensitive variables must not be writable Vast areas of kernel memory contain function pointers that are looked
diff --git a/arch/Kconfig b/arch/Kconfig
index 99839c2..3f8b8be 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig@@ -781,4 +781,38 @@ config VMAP_STACK the stack to map directly to the KASAN shadow map using a formula that is incorrect if the stack is in vmalloc space. +config ARCH_OPTIONAL_KERNEL_RWX + def_bool n + +config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT + def_bool n + +config ARCH_HAS_STRICT_KERNEL_RWX + def_bool n + +config DEBUG_RODATA + bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX + depends on ARCH_HAS_STRICT_KERNEL_RWX + default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT + help + If this is set, kernel text and rodata memory will be made read-only, + and non-text memory will be made non-executable. This provides + protection against certain security exploits (e.g. executing the heap + or modifying text) + + These features are considered standard security practice these days. + You should say Y here in almost all cases. + +config ARCH_HAS_STRICT_MODULE_RWX + def_bool n + +config DEBUG_SET_MODULE_RONX + bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX + depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES + default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT + help + If this is set, module text and rodata memory will be made read-only, + and non-text memory will be made non-executable. This provides + protection against certain security exploits (e.g. writing to text) + source "kernel/gcov/Kconfig"
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 186c4c2..8748353 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig@@ -4,10 +4,14 @@ config ARM select ARCH_CLOCKSOURCE_DATA select ARCH_HAS_DEVMEM_IS_ALLOWED select ARCH_HAS_ELF_RANDOMIZE + select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL + select ARCH_HAS_STRICT_MODULE_RWX if MMU select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_HAVE_CUSTOM_GPIO_H select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_MIGHT_HAVE_PC_PARPORT + select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX + select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_USE_BUILTIN_BSWAP select ARCH_USE_CMPXCHG_LOCKREF
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index d83f7c3..426d271 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug@@ -1738,17 +1738,6 @@ config PID_IN_CONTEXTIDR additional instructions during context switch. Say Y here only if you are planning to use hardware trace tools with this kernel. -config DEBUG_SET_MODULE_RONX - bool "Set loadable kernel module data as NX and text as RO" - depends on MODULES && MMU - ---help--- - This option helps catch unintended modifications to loadable - kernel module's text and read-only data. It also prevents execution - of module data. Such protection may interfere with run-time code - patching and dynamic kernel tracing - and they might also protect - against certain classes of kernel exploits. - If in doubt, say "N". - source "drivers/hwtracing/coresight/Kconfig" endmenu
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index f68e8ec..419a035 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig@@ -1051,18 +1051,6 @@ config ARCH_SUPPORTS_BIG_ENDIAN This option specifies the architecture can support big endian operation. -config DEBUG_RODATA - bool "Make kernel text and rodata read-only" - depends on MMU && !XIP_KERNEL - default y if CPU_V7 - help - If this is set, kernel text and rodata memory will be made - read-only, and non-text kernel memory will be made non-executable. - The tradeoff is that each region is padded to section-size (1MiB) - boundaries (because their permissions are different and splitting - the 1M pages into 4K ones causes TLB performance problems), which - can waste memory. - config DEBUG_ALIGN_RODATA bool "Make rodata strictly non-executable" depends on DEBUG_RODATA
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1117421..e1efbcc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig@@ -13,6 +13,8 @@ config ARM64 select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV select ARCH_HAS_SG_CHAIN + select ARCH_HAS_STRICT_KERNEL_RWX + select ARCH_HAS_STRICT_MODULE_RWX select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_USE_CMPXCHG_LOCKREF select ARCH_SUPPORTS_ATOMIC_RMW
@@ -123,9 +125,6 @@ config ARCH_PHYS_ADDR_T_64BIT config MMU def_bool y -config DEBUG_RODATA - def_bool y - config ARM64_PAGE_SHIFT int default 16 if ARM64_64K_PAGES
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index d1ebd46..939815e 100644
--- a/arch/arm64/Kconfig.debug
+++ b/arch/arm64/Kconfig.debug@@ -71,17 +71,6 @@ config DEBUG_WX If in doubt, say "Y". -config DEBUG_SET_MODULE_RONX - bool "Set loadable kernel module data as NX and text as RO" - depends on MODULES - default y - help - Is this is set, kernel module text and rodata will be made read-only. - This is to help catch accidental or malicious attempts to change the - kernel's executable code. - - If in doubt, say Y. - config DEBUG_ALIGN_RODATA depends on DEBUG_RODATA bool "Align linker sections up to SECTION_SIZE"
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 3a71f38..ad294b3 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig@@ -8,6 +8,7 @@ config PARISC select HAVE_SYSCALL_TRACEPOINTS select ARCH_WANT_FRAME_POINTERS select ARCH_HAS_ELF_RANDOMIZE + select ARCH_HAS_STRICT_KERNEL_RWX select RTC_CLASS select RTC_DRV_GENERIC select INIT_ALL_POSSIBLE
diff --git a/arch/parisc/Kconfig.debug b/arch/parisc/Kconfig.debug
index 68b7cbd..0d856b9 100644
--- a/arch/parisc/Kconfig.debug
+++ b/arch/parisc/Kconfig.debug@@ -5,15 +5,4 @@ source "lib/Kconfig.debug" config TRACE_IRQFLAGS_SUPPORT def_bool y -config DEBUG_RODATA - bool "Write protect kernel read-only data structures" - depends on DEBUG_KERNEL - default y - help - Mark the kernel read-only data as write-protected in the pagetables, - in order to catch accidental (and incorrect) writes to such const - data. This option may have a slight performance impact because a - portion of the kernel code won't be covered by a TLB anymore. - If in doubt, say "N". - endmenu
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index c6722112..53bb0e3 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig@@ -62,9 +62,6 @@ config PCI_QUIRKS config ARCH_SUPPORTS_UPROBES def_bool y -config DEBUG_RODATA - def_bool y - config S390 def_bool y select ARCH_HAS_DEVMEM_IS_ALLOWED
@@ -73,6 +70,8 @@ config S390 select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV select ARCH_HAS_SG_CHAIN + select ARCH_HAS_STRICT_KERNEL_RWX + select ARCH_HAS_STRICT_MODULE_RWX select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_HAVE_NMI_SAFE_CMPXCHG select ARCH_INLINE_READ_LOCK
diff --git a/arch/s390/Kconfig.debug b/arch/s390/Kconfig.debug
index 26c5d5be..57f8ea9 100644
--- a/arch/s390/Kconfig.debug
+++ b/arch/s390/Kconfig.debug@@ -17,7 +17,4 @@ config S390_PTDUMP kernel. If in doubt, say "N" -config DEBUG_SET_MODULE_RONX - def_bool y - depends on MODULES endmenu
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e487493..13e1bf4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig@@ -54,6 +54,8 @@ config X86 select ARCH_HAS_MMIO_FLUSH select ARCH_HAS_PMEM_API if X86_64 select ARCH_HAS_SG_CHAIN + select ARCH_HAS_STRICT_KERNEL_RWX + select ARCH_HAS_STRICT_MODULE_RWX select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_HAVE_NMI_SAFE_CMPXCHG select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
@@ -309,9 +311,6 @@ config ARCH_SUPPORTS_UPROBES config FIX_EARLYCON_MEM def_bool y -config DEBUG_RODATA - def_bool y - config PGTABLE_LEVELS int default 4 if X86_64
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 67eec55..69cdd0b 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug@@ -109,17 +109,6 @@ config DEBUG_WX If in doubt, say "Y". -config DEBUG_SET_MODULE_RONX - bool "Set loadable kernel module data as NX and text as RO" - depends on MODULES - ---help--- - This option helps catch unintended modifications to loadable - kernel module's text and read-only data. It also prevents execution - of module data. Such protection may interfere with run-time code - patching and dynamic kernel tracing - and they might also protect - against certain classes of kernel exploits. - If in doubt, say "N". - config DEBUG_NX_TEST tristate "Testcase for the NX non-executable stack feature" depends on DEBUG_KERNEL && m
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2.7.4